Prp43 is an essential RNA-dependent ATPase required for release of lariat-intron from the spliceosome.

TitlePrp43 is an essential RNA-dependent ATPase required for release of lariat-intron from the spliceosome.
Publication TypeJournal Article
Year of Publication2002
AuthorsMartin A, Schneider S, Schwer B
JournalJ Biol Chem
Date Published2002 May 17
KeywordsAdenosine Triphosphatases, Adenosine Triphosphate, DEAD-box RNA Helicases, DNA Mutational Analysis, Electrophoresis, Polyacrylamide Gel, Introns, Mutagenesis, Site-Directed, Phenotype, RNA Helicases, RNA Nucleotidyltransferases, RNA, Fungal, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Spliceosomes

The essential Saccharomyces cerevisiae PRP43 gene encodes a 767-amino acid protein of the DEXH-box family. Prp43 has been implicated in spliceosome disassembly (Arenas, J. E., and Abelson, J. N. (1997) Proc. Natl. Acad. Sci. U. S. A. 94, 11798-11802). Here we show that purified recombinant Prp43 is an RNA-dependent ATPase. Alanine mutations at conserved residues within motifs I ((119)GSGKT(123)), II ((215)DEAH(218)) and VI ((423)QRAGRAGR(430)) that diminished ATPase activity in vitro were lethal in vivo, indicating that ATP hydrolysis is necessary for the biological function of Prp43. Overexpression of lethal, ATPase-defective mutants in a wild-type strain resulted in dominant-negative growth inhibition. The ATPase-defective mutant T123A interfered in trans with the in vitro splicing function of wild-type Prp43. T123A did not affect the chemical steps of splicing or the release of mature mRNA from the spliceosome, but it blocked the release of the excised lariat-intron from the spliceosome. We show that the lariat-intron is not accessible to debranching by purified Dbr1 when it is held in the T123A-arrested splicing complex. Our results define a new ATP-dependent step of splicing that is catalyzed by Prp43.

Alternate JournalJ. Biol. Chem.
PubMed ID11886864
Grant ListGM50288 / GM / NIGMS NIH HHS / United States

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